A microbe UW-Madison researchers found in an abandoned mine may provide the key to creating virtually unbreakable materials.
In a study published in the March 12 issue of Science, researchers from UW-Madison and the University of California-Berkeley described the structure and formation of the long, willowy crystals the microbe creates.
The microbe, discovered in the flooded tunnels of an old iron mine in Tennyson, Wis., uses polysaccharides-organic substances formed by strings of sugar molecules-to create a template on its cell surface for the formation of a crystal that is more than 1,000 times longer than it is wide.
\What's unique about these crystals is that they're very thin and very long,"" said Gelsomina De Stasio, a UW-Madison professor of physics and lead author of the study. ""[They have] the same aspect ratio as human hair.""
The crystals are composed of inorganic iron molecules in a single strand connected to the microbe by the polysaccharide template in a process called biomineralization-living creatures creating non-living minerals. It is hypothesized that these microbes produce the crystals to create energy.
""These products are interesting because they are so novel,"" said Jillian Banfield, a professor of Earth and planetary science at UC-Berkeley and the senior scientist in the study. ""They indicate the influences of biomolecules on crystallization.""
A similar process creates shells, teeth and bones, but scientists have not been able to study in depth the process by which these materials are created because of the difficulty of studying organic and inorganic molecules together.
A new technique called X-ray spectromicroscopy makes this possible. The process uses X-rays and a special type of microscope to examine both organic and inorganic molecules in a sample. This practical application of the technique was demonstrated for the first time in this study, De Stasio said.
The discovery, Banfield said, could ultimately inspire new ways of creating materials by mimicking processes in nature, such as the crystallization done by these microbes.
For instance, mollusks can create shells that are more than 3,000 times stronger than the mineral used to make them normally is. To do this on a practical, human scale would be an important breakthrough, De Stasio said.
""If we could understand the interaction between these inorganic and organic molecules, we could produce materials that are unbreakable,"" she said.
